In the past, several attempts have been made to produce plastic components having high physical strength and resistance against breakage and distortion while rendering the component made of such synthetic resin lightweight and easy to recycle. In particular, in the luggage industry, there is a demand for producing hard shell suitcases combining the highest reliability and resistance against impact from outside with distortion-free behavior, favorable appearance, and reduced weight to allow such luggage to be handled with ease and convenience.
EP 0531473B1 provides a process and material in which an assembly of oriented polymeric fibers is maintained in intimate contact at an elevated temperature so that outer areas of the oriented polymeric fibers melt, and the fibers are subsequently compressed so as to produce a coherent polymer sheet. According to the method and material, the thermoplastic material of polyolefin, in particular, polypropylene or other crystalline or semi-crystalline materials, can be arranged as uni-axially aligned bundles or twisted bundles of fibers or as a woven mat of interwoven bundles depending on the later field of application.
From U.S. Pat. No. 5,376,322, a process of thermo-forming, a cloth covered shape from a preform is known for producing luggage shells by pressure laminating a layer of cloth fabric to one surface of a thermoplastic substrate, which subsequently undergoes a press forming process in a mold press with a specific focus on the forming of the corner areas.
Also, U.S. Patent Publication No. 2008/0261471, entitled “Polyolefinic Materials for Plastic Composites,” discloses woven polymeric fibers. One of the commercial woven fabrics is CURV®, which is made from polypropylene, and has high stiffness, high tensile strength and high impact resistance at low density. CURV® material is used for producing luggage shells, however it is very expensive. The problem with the woven fabrics is the complexity and cost of production.
Another method is to produce luggage shells from compression molding a plastic sheet, such as an acrylonitrile butadiene styrene (ABS) sheet. It is desirable to improve strength/reduce thickness of such luggage shells. Also, the luggage shell may be injection molded. However, injection molding requires expensive tooling.
Additional documents which disclose woven fibers and non-woven fibers are: U.S. Pat. No. 4,908,176, U.S. Pat. No. 8,202,942, U.S. Pat. Publication No. 2011/0253152, EP181470, EP2576881, and EP2311629. These proposals, however, may not be suitable for use in luggage items, or may be improved.
It is therefore desirable to provide an improved luggage construction, in particular an improved luggage, which addresses the above described problems and/or which more generally offers improvements or an alternative to existing sheet material structure and forming methods.